Journal of the Mass Spectrometry Society of Japan
Online ISSN : 1880-4225
Print ISSN : 1340-8097
ISSN-L : 1340-8097
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Volume 34, Issue 4
Displaying 1-5 of 5 articles from this issue
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REGULAR PAPERS
  • Computer-assisted Null Point Method for the Mass Spectrometric Measurement of Relative Abundance of Hydrogen Isotopes
    Takashi Ohsumi, Jun Tamura
    1986 Volume 34 Issue 4 Pages 197-206
    Published: 1986
    Released on J-STAGE: May 01, 2007
    DOIhttps://doi.org/10.5702/massspec.34.197
    JOURNAL FREE ACCESS
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    A multiplying digital-to-analog converter (DAC) has been incorporated into the measuring circuit of a conventional double collector mass spectrometer. Inverse feedback of a portion of the signal from the mass-2 peak (H2+) is controlled by the microcomputer so as to exactly cancel the ion current signal of the mass-3 peak (HD+ + H3+). The control to obtain the null point was so successful that we can regard the digital number being sent to the DAC as the proportional value to the ion current ratio. The software simulation of gas exchange in the ionization chamber from the sample gas to the reference gas and vice versa brought about the reduction of the measurement time.
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  • Study on the Fragmentation Mechanism of Isopropyl Methacrylate
    Tamae Yanagisawa, Seiji Tobita, Susumu Tajima, Hirokazu Hanaoka
    1986 Volume 34 Issue 4 Pages 217-224
    Published: 1986
    Released on J-STAGE: May 01, 2007
    DOIhttps://doi.org/10.5702/massspec.34.217
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    Fragmentation mechanism of the molecular ion of isopropyl methacrylate has been investigated by using kinetic energy release measurement, deuterium labelling technique and mass analyzed ion kinetic energy spectrometry. The methyl radical is eliminated from the molecular ion with a "hidden" hydrogen migration, not a simple cleavage. Further, it is demonstrated that the two hydrogen atoms in double hydrogen migration originate from the individual methyl groups in isopropyl group in the ion source.
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  • New Interface for Direct Liquid Introduction LC/MS
    Tokuo Mizuno, Kenji Matsuura, Koushi Azuma
    1986 Volume 34 Issue 4 Pages 225-233
    Published: 1986
    Released on J-STAGE: May 01, 2007
    DOIhttps://doi.org/10.5702/massspec.34.225
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    The nebulizer of a direct liquid introduction (DLI) LC/MS interface has been improved. A straight and stable jet was obtained for a long time, and the basic performance of the interface thus increased is discussed. The validity of the interface was demonstrated in its application to taking mass spectra of thermally labile and/or non-volatile compounds.
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  • Application of Direct Liquid Introduction LC/MS Negative CI Mass Spectra
    Tokuo Mizuno, Kenji Matsuura, Koushi Azuma
    1986 Volume 34 Issue 4 Pages 235-242
    Published: 1986
    Released on J-STAGE: May 01, 2007
    DOIhttps://doi.org/10.5702/massspec.34.235
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    An on-line LC/MS system with a semimicro HPLC and a direct liquid introduction LC/MS interface was applied to the investigation of both positive and negative chemical ionization mass spectra of compounds that contain hydroxyl and carboxyl functional groups or halogen atoms. These mass spectra had a characteristic of yielding significant quasi-molecular ions (M+H)+ and (M-H)-, and the molecular ion M- corresponding to their molecular structure. Furthermore, this LC/MS system was experimentally proved to provide LC/MS routine analysis capability for some drugs which contain several components, making it possible to separate those components and determine their molecular weights.
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  • Analysis of Free- and PTH-Amino Acids by HPLC/MS with Self-Spouting and Vacuum Nebulizing Assisted Interface
    Kozo Matsumoto, Shin Tsuge
    1986 Volume 34 Issue 4 Pages 243-248
    Published: 1986
    Released on J-STAGE: May 01, 2007
    DOIhttps://doi.org/10.5702/massspec.34.243
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    A high performance liquid chromatography and mass spectrometry (HPLC/MS) combination system with a self-spouting and vacuum nebulizing assisted interface was applied to measure the chemical ionization (CI) mass spectra of free- and PTH- amino acids. An aliquot of the injected sample solution carried to the interface with flow of a molbile phase (100 μl/min) was nebulized under a reduced pressure, and introduced into an ion source where the vapour of the mobile phase was used as a reagent gas for CI. The CI mass spectra of twenty kinds of free amino acids were measured using water as a mobile phase. The mass spectra for fifteen kinds of PTH amino acids which eluted successively from a separation column were also obtained using a mixture of acetonitrile and water of 3:1 (v/v) ratio as a mobile phase.
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